Window designs for passenger vehicles such as recreational vehicles (“RV's”), busses, and railroad cars can provide alternate means of exiting in case of an emergency. Typically, such windows include a framed panel attached via a hinge to the wall of the vehicle, and a latch assembly. The window can be quickly unlatched and pivoted outward, allowing passengers to exit the vehicle by way of the window.
The latches of these windows must typically meet stringent specifications. They must hold the window in place with sufficient force to provide a watertight seal and minimize vibrations and noise, yet provide for easy unlatching. They should ideally extend into the interior of the vehicle as little as possible so as not to reduce usable interior space. Further, they must meet the requirements of Federal Motor Vehicle Safety Specifications, including, for example, FMVSS 217. Additionally, they should be able to provide constant latch engagement despite manufacturing tolerance stack-up. Finally, they should be inexpensive to produce, install, and maintain.
Commercially available latches for vehicle egress windows do not meet all of these requirements. One type of latch mechanism is seen in FIGS. 12–13, where it is shown without the window with which the assembly is associated. A latch bolt 100 includes a lower extension 102 having a triangular cross-section that, when in a first position, engages an upwardly-biasing leaf spring 104. One face of latch bolt 100 is connected to a handle 106, and its opposite face is connected to a horizontally-biasing spring 108. Rotation of handle 106 actuates latch bolt 100, pulling it horizontally and monolinearly from a first latched position, seen in FIG. 12, to a second unlatched position, seen in FIG. 13, such that lower extension 102 slides off of leaf spring 104, permitting the window to be swung outwardly to an open position. Horizontally-biasing spring 108 pulls latch bolt 100 back to the latched position upon the window being opened and handle 106 being released. Upon shutting, triangular lower extension 102 slides up an angled portion of leaf spring 104, which compresses until lower extension 102 clears the top of leaf spring 104, at which point leaf spring 104 snaps upward and reengages lower extension 102, relatching the window without any further manipulation of the latch mechanism. This automatic relatching upon shutting the window is known as “slam-shut,” and is desirable in that it requires less time and effort to latch the windows after opening them.
Another common latch mechanism for a window assembly includes keepers mounted on a structural frame around a window opening and pivotable members mounted on the rim of the window that snap over the keepers. This design is inexpensive, but requires two hands to operate, which is impractical and will not meet current specifications on certain typical larger windows. The keepers require mounting holes and fasteners and usually the removal of trim. The keepers are of such a size that they project inwardly of the vehicle an amount that presents a hazard to passengers exiting through the window, and interferes with seating space. Further, the design will not withstand variances in manufacturing tolerance stack up, and require constant adjustment of the keepers to provide the requisite snap action. The degree of force required to open and close the latches is quite high.
Another type of latch mechanism is described in U.S. Pat. No. 3,927,492 to Carson. In Carson, an inner window frame and an outer window frame support a window, and the latching mechanism has an articulated linkage that folds into a contoured channel of the inner window frame in a way that latches the window shut. An actuating lever, which comprises a facing or trim molding extension, actuates the latch to a release position. The molding is pulled downward, levering the linkages out of the latched position and permitting the window to be opened. In this mechanism, no biasing means are present to return the latch automatically to the latched position, thus, “slam-shut” operation is not possible.
The latch mechanism of U.S. Pat. No. 4,635,396 to Ranz et al. is similar to that of Carson in that the latch involves a series of linkages and a molding piece that acts as an actuating lever. In this mechanism, the linkages move with the window when it is opened, and there is a shoulder mounted to a bottom support that engages with the latch bolt to latch the window shut. The Ranz latch is opened by pulling the molding upward, thus disengaging the latch bolt from the shoulder. As with Carson, no biasing means are present to permit the latch to close automatically and provide for “slam-shut” operation.
It is an object of the present invention to provide a latching mechanism that reduces or wholly overcomes some or all of the difficulties inherent in prior known devices. Particular objects and advantages of the invention will be apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this field of technology, in view of the following disclosure of the invention and detailed description of certain preferred embodiments.